When tape in an audio cassette jams, it is usually due to slack tape in the cassette. The presence of slack tape is not always visually apparent and is often caused by failure to properly store the cassettes in boxes that have tabs to lock the hubs that carry the coils of tape. When the hubs are not locked, the coil of tape within the cassette tends to unwind inside the cassette housing. Ordinarily, when a user inserts a tape cassette in a tape deck, the pinch roller and the capstan trap the tape therebetween and start pushing the tape towards the take-up hub and the hub, which turns faster than the capstan, will always keep the tape taut. However, when there is a build-up of slack tape on the take-up side of the cassette, the pinch roller and the capstan will tend to start pushing the tape out of its normal feed path while it is waiting for the take-up hub to wind all the slack out of the coil of tape. It is during this time period when most tape jams occur.
During a tape jam, the tape usually starts to build-up in an area between the nip (between the capstan and pinch roller) and one of the hubs. After a few loops of tape form in this area, a loop of tape will take one of two paths. First, it will shoot out past the pinch roller and start dumping tape into the mechanical workings of the tape deck. See for example, prior art FIG. 3. This can lead to a situation where the tape will jam the mechanical workings of the tape deck, requiring that the tape deck be serviced to have the tape and cassette properly removed. The second path that the tape may take is to work its way back into the capstan area in front of the capstan. When this happens, the capstan will grab the tape loop along with additional tape from the supply hub of coiled tape and cause a "capstan wrap" jam. This is shown, for example, in prior art FIG. 4. This type of jam will also require service because the cassette is locked on the capstan by the tape and cannot be ejected from the tape deck.
U.S. Pat. No. 4,232,350 issued to Ohta discloses a shield member 20 positioned between a guide bracket 19' and guide pin 18' within the cassette housing. Upon loosening of the turns of tape making up a tape coil, the shield member prevents contact of a guide roller 16' with the outermost loosened turn. Nevertheless, the bracket guide 19' associated with the capstan is of standard construction and is in parallel spaced relationship with the tape feed path.
Dutch Patent 7,810,894 to Geva discloses a tape cassette where jamming of the tape at the transfer from one side to the other is prevented by a slanting ridge 5 of a length such that the slot 6 formed between the slanting ridge and the side of the cassette will only be approximately 1 millimeter. The guide bracket 1 associated with the capstan is of standard construction and is positioned parallel to the tape feed path.